1. Field of the Invention
This invention relates to a band saw machine, particularly to one provided with a band saw changing device, wherein a quickly adjusting device is added for quick adjustment for changing a band saw.
2. Description of the Prior Art
As shown in FIG. 1, a conventional band saw changing device 10 in a band saw machine includes a sliding base 11, two limiting bases 12 for the sliding base 11 to sliding between them, a shaft fixing base 111 fitted in an upper portion of the sliding base 11, a shaft 112 of the shaft fixing base 111 being connected to a turning wheel 1, a limiting member 113 laterally fixed in an intermediate portion of the sliding base 11, a spring 13 located under the limiting member 113, a support disc 14 supporting the spring 13, a micro adjusting rod 15 having a guide threaded portion 151 formed on an upper portion and threadably combined with a threaded hole 141 of the support disc 14 to further pass through the spring 13 and the limiting member 113, and a bottom base 16 fixed under the two limiting bases 12. The micro-adjusting rod 15 passes through the bottom base 16, and a ring 152 is pivotally connected to the micro-adjusting rod 15 just on the bottom base 16. The micro-adjusting rod 15 is provided with a hand wheel 153 at the lower end.
In using, when the hand wheel 153 is turned clockwise or counterclockwise, the guide threaded portion 151 of the micro adjusting rod 15 is rotated to move the support disc 14 upward or downward, so the shaft fixing block 111 of the sliding base 11 and the turning wheel 1 may be moved up or down accordingly, increasing or reducing the distance between the turning wheel 1 and a lower wheel for tightening or loosening for taking off a band saw extending around the two turning wheels. However, when the conventional band saw changing device 10 is handled to change the band saw, the turning wheel 153 of the micro-adjusting rod 15 is rotated to move the sliding base 11 along between the two limiting bases 12. But the guide threaded portion 151 moves up or down for a very minute distance by rotation, so one round of the hand wheel 153 may force the sliding base 11 to move up or down only a bit, taking a rather long time needed in rotating the hand wheel 153 before the band saw can be taken off. Accordingly, tightening a new band saw also needs a long time, not ideal for operating the conventional band saw changing device 10.